linux-kernel - [PATCH 3.16.y-ckt 127/133] usbnet: Get EVENT_NO_RUNTIME

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Date:	Wed, 30 Sep 2015 10:51:15 +0100
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Eugene Shatokhin <eugene.shatokhin@...alab.ru>,
	"David S. Miller" <davem@...emloft.net>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 127/133] usbnet: Get EVENT_NO_RUNTIME_PM bit before it is cleared

3.16.7-ckt18 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eugene Shatokhin <eugene.shatokhin@...alab.ru>

commit f50791ac1aca1ac1b0370d62397b43e9f831421a upstream.

It is needed to check EVENT_NO_RUNTIME_PM bit of dev->flags in
usbnet_stop(), but its value should be read before it is cleared
when dev->flags is set to 0.

The problem was spotted and the fix was provided by
Oliver Neukum <oneukum@...e.de>.

Signed-off-by: Eugene Shatokhin <eugene.shatokhin@...alab.ru>
Acked-by: Oliver Neukum <oneukum@...e.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 drivers/net/usb/usbnet.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index c5a2ad29d53c..5d819dde448d 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -778,7 +778,7 @@ int usbnet_stop (struct net_device *net)
 {
 	struct usbnet		*dev = netdev_priv(net);
 	struct driver_info	*info = dev->driver_info;
-	int			retval, pm;
+	int			retval, pm, mpn;
 
 	clear_bit(EVENT_DEV_OPEN, &dev->flags);
 	netif_stop_queue (net);
@@ -809,6 +809,8 @@ int usbnet_stop (struct net_device *net)
 
 	usbnet_purge_paused_rxq(dev);
 
+	mpn = !test_and_clear_bit(EVENT_NO_RUNTIME_PM, &dev->flags);
+
 	/* deferred work (task, timer, softirq) must also stop.
 	 * can't flush_scheduled_work() until we drop rtnl (later),
 	 * else workers could deadlock; so make workers a NOP.
@@ -819,8 +821,7 @@ int usbnet_stop (struct net_device *net)
 	if (!pm)
 		usb_autopm_put_interface(dev->intf);
 
-	if (info->manage_power &&
-	    !test_and_clear_bit(EVENT_NO_RUNTIME_PM, &dev->flags))
+	if (info->manage_power && mpn)
 		info->manage_power(dev, 0);
 	else
 		usb_autopm_put_interface(dev->intf);
--
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